Restriction digests of the clone give the following sizes (kb): SacI/XbaI--3.9 (doublet); EcoRI--5.1, 2.4; KpnI--5.8, 1.7. It appears that the SacI site at the start of the GAL1 promoter has been lost.

Expression from the galactokinase (GAL1) promoter is tightly repressed by glucose and is strongly induced by galactose.